Monday, June 14, 2010
Douglass F. Taber
University of Delaware
Benzene Derivatives: The Tanino-Miyashita Synthesis of Zoanthenol
Yuqing Hou of Southern Illinois University found (J. Org. Chem. 2009, 74, 6362. ) that the peroxy ether 2 served effectively to directly transfer a methoxy group to the lithiated 1 to give 3. Wanzhi Chen of Zhejiang University, Xixi Campus, showed (J. Org. Chem. 2009, 74, 7203. ) that pyrimidines such as 4, readily prepared from the corresponding phenol, underwent smooth Pd-catalyzed ortho acetoxylation.
Trond Vidar Hansen of the University of Oslo observed (Tetrahedron Lett. 2009, 50, 6339. ) that simple electrophilic formylation of phenols such as 6 also proceeded with high ortho selectivity. Kyung Woon Jung of the University of Southern California optimized (J. Org. Chem. 2009, 74, 6231. ) the Rh catalyst for ortho C-H insertion, converting 8 into 9.
Jin-Quan Yu of Scripps/La Jolla devised (Science 2010, 327, 315. ) a protocol for carboxy-directed catalytic ortho palladation that allowed subsequent Heck coupling, transforming 10 into 11. Norikazu Miyoshi of the University of Tokushima established (Chem. Lett. 2009, 38, 996. ) that in situ generated strontium alkyls added 1,6 to benzoic acid 13, to give, after mild oxidative workup, the 4-alkyl benzoic acid 15.
Amin Zarei of Islamic Azad University showed (Tetrahedron Lett. 2009, 50, 4443. ) that their previously-developed protocol for preparing stable diazonium silica sulfates could be extended to the preparation of an aryl azide such as 17. Stephen L. Buchwald of MIT developed (J. Am. Chem. Soc. 2009, 131, 12898. ) a Pd-mediated protocol for the conversion of aryl chlorides to the corresponding nitro aromatics. Virgil Percec of the University of Pennsylvania has also reported (Org. Lett. 2009, 11, 4974. ) the conversion of an aryl chloride to the borane, and Guy C. Lloyd-Jones has described (Angew. Chem. Int. Ed. 2009, 48, 7612. ) the conversion of phenols to the corresponding thiols.
Kwang Ho Song of Korea University and Sunwoo Lee of Chonnam National University demonstrated (J. Org. Chem. 2009, 74, 6358. ) that the Ni-mediated homologation of aryl halides worked with a variety of primary and secondary formamides. Kwangyong Park of Chung-Ang University observed (J. Org. Chem. 2009, 74, 9566. ) that nickel catalysts also mediated the coupling of Grignard reagents with the tosylate 22 not in the usual way, but with the C-S bond, to give 23.
Martin D. Burke of the University of Illinois reported (J. Am. Chem. Soc. 2009, 131, 6961. ) that the derivative 25 served as a useful slow-release source for otherwise unstable boronic acids. Gary A. Molander of the University of Pennsylvania took advantage (Org. Lett. 2009, 11, 2369. ) of the marked difference in reactivity of the two boranes of 28 to effect sequential coupling.
It is sometimes most efficient to construct the aromatic ring. This is illustrated by the tautomerization of 31 to 32, the key step in the total synthesis of Zoanthenol (33) reported (Angew. Chem. Int. Ed. 2009, 48, 8905. ) by Keiji Tanino and Masaaki Miyashita of Hokkaido University.
D. F. Taber, Org. Chem. Highlights 2010, June 14.